As this kind of technique, there is disclosed a technique discussed in the following patent literature, PTL 1. PTL 1 discloses a torque sensor that detects a torque by detecting, with use of a magnetic sensor, a change in a magnetic flux passing through between magnetic collection rings adjacent to each other in a radial direction with respect to an input shaft due to a relative rotation between the input shaft and an output shaft connected to each other via a torsion bar.